Sustainable Synthesis and Interfacial Engineering of Graphene Quantum Dot Photocatalysts for Advanced Water Purification

ABSTRACT

Graphene quantum dots (GQDs) are promising photocatalytic nanomaterials for sustainable water purification because of their tunable electronic structure, abundant active sites, and efficient interfacial charge‐transfer capability. This review critically examines sustainable synthesis and interface‐engineering strategies for GQD‐based photocatalysts, with emphasis on the structure–property relationships governing their performance. Biomass‐derived, hydrothermal, microwave‐assisted, and ultrasound‐mediated routes are evaluated in terms of structural control, environmental impact, reproducibility, and scalability. The roles of quantum confinement, defects, edge chemistry, and surface interactions in charge separation, reactive oxygen species generation, and pollutant degradation are also discussed. Unlike previous reviews that primarily catalogue synthesis methods or photocatalytic efficiencies, this work establishes an integrated synthesis–structure–interface–performance framework linking precursor selection, electronic structure, interfacial charge utilization, catalyst stability, and realistic water‐treatment deployment. Evidence from dye degradation, volatile organic compound removal, and complex aqueous remediation indicates that performance depends on the combined effects of adsorption, surface reactivity, and interfacial electron dynamics. Finally, life‐cycle sustainability, catalyst recovery, fouling, scalable production, and circular treatment integration are critically assessed to guide the practical advancement of GQD photocatalysts.